Analysis of Astringent Components and Differential Gene Expression of Related Key Enzymes in Different Tissues of Fresh Lotus Seeds

This study was performed to explore the differences in the composition of astringent substances in different tissues of fresh lotus seeds and the expression of key enzyme genes involved in the synthesis of astringent compounds. The contents of soluble tannins, insoluble tannins and proanthocyanidins in lotus seed coat, lotus seed pulp without coat and lotus seed plumule were determined. Meanwhile, the activity and gene expression of key enzymes in the tannin synthesis pathway were detected. Sensory evaluation and electronic tongue analysis were performed on lotus seed samples. The data obtained was analyzed by orthogonal partial least squares discriminant analysis (OPLS-DA) and correlation analysis. Results showed that the major substance contributing to the astringency of lotus seeds was soluble tannins. Tannins had a positive effect on its excellent flavor at the waxy ripeness stage. Anthocyanin reductase was a key enzyme affecting the astringency intensity of lotus seeds. SnANR9 played a role in regulating the astringency of different tissues of lotus seeds.